Preparation of ethylene oxide



V Patented Nov. 26, 1935 I 2,022,182 PREPARATION 0F ETHYLENE oxnm EdgarC. Britten, Gerald H. Coleman, and Byron Mate, Midland,'Mich., assignorsto The Dow Chemical Company, Midland, Mich., a corporation of MichiganNo Drawing. Application May 12, 1934,

Serial No. 725,316

8 Claims. (c1. 260 -54) The present invention regards an improvement inmethods for the preparation of ethylene oxide. I

We have found that the reaction between betachloroethylacetate and analkali metal hydroxide produces either ethylene oxide or glycol, or bothi in varying proportions. The proportions of these two compounds intheproduct from the foregoing reaction varies widely, depending upon theconditions in which the reaction is carried out. Moreover, the reactionmay be very rapid, particularly in the presence of an excess of thehydroxide, and the highreaction velocity makes it very diflicult tocontrol the course of the reaction so as to produce a good yield ofethylene oxide. The yield of ethylene oxide is also affected by theconcentration of the metal hydroxide.

We have now found that, under certain conditions, the formation ofglycol is materially suppressed and the reaction proceeds chiefly to theformation of ethylene oxide. It is, therefore, an object of thisinvention to provide suitable conditions under which the reactionbetween betachloroethylacetate and a base, such as an alkali metal oralkaline earth metal hydroxide or carbonate, can be carried out toproduce a maximum yield of ethylene oxide while avoiding substantiallythe formation of glycol.

To the accomplishment of the foregoing and related ends, we have nowfound that the difficulties and uncertainties formerly encountered inproducing a good yield of ethylene oxide by the aforesaid reaction areavoided if the base is gradually added to the beta-chloroethylacetate,while vigorously agitating the reaction mixture, and maintaining it at atemperature between about 40 and about 150 C. In this manner we at alltimes avoid the presence of an excess of unreacted base in the reactionmixture. Then, by such procedure the reaction is made practicallyindependent of the concentration of base employed. Thus, theconcentration of the aqueous base may be varied between wide limits, e.g. from as low as 10 per cent thereof up to or per cent by weight, thechoice of concentration being largely a matter of convenienceandeconomy. The following examples show the results obtained by carryingout the reaction between beta-chloroethylacetate and an alkali metal oralkaline earth metal base at varying temperatures and with differentconcentrations thereof.

tate was placed in a round-bottom flask provided with a stirrer and areflux condenser. The flask was then heated to and maintained at thevarious temperatures shown-in the following Table I while 2.2 moles ofsodium hydroxide in a 20 per cent aqueous solution was gradually addedthereto 5 over the periods of time shown. The reaction mixture wasvigorously stirred throughout the reaction period. The yield of ethyleneoxide is in per cent of theoretical based on the beta-chloroethylacetatereacted,'which' was in all cases above 10 95 percent.

Table I I Percent Reaction Timem yield of mm gag? minutes ethylene 15oxide EzwmplcZ The following Table II shows the yield of ethyl- 25 eneoxide obtained during a series of runs carried out as above wherein thetemperature was held constant at (3., but the concentration of sodiumhydroxide ,was varied.

Table II 30 C(1tiicentfra- T Perlcienif;

on 0 me in me 0 Run sodium minutes ethylene hydroxide oxide 40 Example 3We have carried out the preparation of ethylene oxide using 1.1 moles ofcalcium hydroxide as the base, obtaining a yield of 74.6 per cent oftheoretical based on 9'72 per cent of the beta-chloro- 45 ethylacetatereacted.

Example 4 We have also carried out the preparation of ethylene oxide ata temperature of 100 C., using 60 1.1 moles of sodium carbonate in a 25per cent aqueous solution as the base, to obtain a yield of 60.4 percent of theoretical based on the betachloroethylacetate reacted.

It is a feature of our improved method that 55 ea-"manualchloroethylacetate was gradually added to a 40 per cent aqueous sodiumhydroxide solution at a temperature of about C., the yield of ethyleneoxide was only 2.7 per cent, the chief-product being ethylene glycol. j

It is readily apparent from the foregoing description of our inventionthat our improved method for the preparation of ethylene oxide providesa procedure capable of producing high yields of the desired compoundwithout the formation of large proportions of undesirable products,particularly glycol. 1 r

Other modes of applying the principle of our invention may beemployed-instead of those explained, change being made as regards theprocess herein disclosed, provided the step or steps stated by any ofthe following claims or the equivalent of such stated step or steps beemployed. V I

We therefore particularly point out and dis-, tinctly claim as ourinvention:--- r 1. In carrying out the preparation of ethylene oxidefrom beta-chloroethylacetate by reaction thereof with a base, the stepwhich consists in gradually adding the base to thebeta-chloroethylacetate, while agitating the reactionmixture andmaintaining it at a temperature between about 40 and about C.

2. In carrying out the preparationof ethylene oxide frombeta-chloroethylacetate by reaction thereof with a hydroxide of analkali forming metal, the step which consists in gradually adding thehydroxide to the beta-chloroethylacetate, While agitating thereactionmixture and maintaining it at a temperature between about 40 and about150 C.

3. In carrying out the preparation of ethylene oxide frombeta-chloroethylacetate by reaction thereof with an alkali metalhydroxide, the step which consists in gradually adding the hydroxide tothe beta-chloroethylacetate, in the molar ratio of about two moles ofhydroxide per mole of the presence of a material excess of unreactedbeta-chloroethylacetate, while agitating the reaction mixture andmaintaining it at a temperature between about 40 and about 150 C.

4. In carrying out the preparation of ethylene oxide frombeta-chloroethylacetate by reaction 5 thereof with an alkali earth metalhydroxide, the step which consists in gradually adding the hydroxide' tothe beta-chloroethylacetate, in the molar ratio of about one mole ofhydroxide per mole of beta-chloroethylacetate, While agitating 10 thereaction mixture and maintaining it at a temperature between about 40and about 150 C.

5. In carrying out the preparation of ethylene oxide frombeta-chloroethylacetate by reaction thereof with an alkali metalhydroxide, the step 15 which consists in gradually adding the hydroxideto -the beta-chloroethylacetate, in the molar ratio of about two molesof hydroxide per mole of beta-chloroethylacetate, while agitatingbetween about 40 and 150 C. 30

7. In carrying out the preparation of ethylene oxide frombeta-chloroethylacetate by reaction thereof with sodium hydroxide, thestep which consists in gradually adding the hydroxide to thebeta-chloroethylacetate, in the molar ratio of 35 about two moles ofhydroxide per mole of betachloroethylacetate, while agitating thereaction mixtureand' maintaining it at a temperature of about 100 C. a r

' 8. In carrying out the preparation of ethylene 40' oxide frombeta-chloroethylacetate by reaction thereof with an aqueous solution ofa base, the step which consists in gradually adding the aque- Oussolution of the base to the beta-chloroethylacetate, while agitating thereaction mixture and 45 maintaining it at a, temperature between about40 and about 150 C.

EDGAR C. BRITTON.

GERALD H. COLEMAN.

BYRON MATE. 50

